Federal land management agencies -- National Park Service, National Fish & Wildlife Service, Bureau of Land Management, U.S. Forest Service, and occasionally others -- are required to recommend to Congress lands they believe qualify for wilderness designation on a state-by-state basis. Congress then decides which areas to designate. In many cases, Congress has designated more lands for wilderness than federal land management agencies recommended.

The Wilderness Act of 1964 directed the Forest Service, National Park Service, and the Fish and Wildlife Service to survey their roadless lands for possible wilderness designation. The Act requires that wilderness areas be "administered for the use and enjoyment of the American people in such a manner as will leave them unimpaired for future use and enjoyment as wilderness."

The Wilderness Act protects Congressionally-designated wilderness areas from roads, dams, or other permanent structures; from timber cutting and the operation of motorized vehicles and equipment; and, since 1984, from new mining claims and mineral leasing.

Two other laws require wilderness reviews on national lands: the Federal Land Policy and Management Act of 1976 (FLPMA) directed the Bureau of Land Management to inventory its roadless lands for wilderness protection; and the Alaska Lands Act of 1980 also called for wilderness reviews.

Mining operations and livestock grazing are permitted to continue in wilderness areas where such operations existed prior to an area's designation. Hunting and fishing are also allowed in wilderness areas (except in national parks), as are a wide range of other non-mechanized recreation, scientific, and outdoor activities.